This invention relates generally to high frequency RF receivers and particularly to a microwave oscillator and mixer arrangement for use in satellite television receiver circuits.
A radio frequency (RF) receiver generally includes an RF amplifier for amplifying a received signal and a form of frequency converter for translating the received signals to a more convenient lower frequency. The frequency converter generally includes a mixer circuit that is supplied with an RF signal and also coupled to a source of reference frequency from a local oscillator. The received RF signal is mixed or heterodyned with the signal from the reference oscillator to generate an intermediate frequency (IF) signal for further processing in the receiver. At higher frequencies in the RF spectrum, expensive hybrid microcircuits are frequently used. They generally include discrete active and passive components sometimes in combination with integrated circuit elements interconnected by means of microstrip conductors, which are short transmission lines.
In the co-pending application of the inventor entitled "Integrated Single Balanced Mixer/Oscillator with Slot and Hybrid Coupler", Ser. No. 456,158, filed Jan. 6, 1983, now U.S. Pat. No. 4,461,040, and assigned to Zenith Radio Corporation, a low cost oscillator/mixer arrangement for a microwave television receiver of approximately 12 gigaHertz for direct satellite reception that avoids many of the expensive fabrication techniques of the prior art is described. For example, in that application, the complex filter circuits for rejection of local oscillator and image frequencies and all critical and discrete, passive devices have been substantially simplified or eliminated.
This invention is an improvement over the oscillator arrangement described in the co-pending application; specifically in the form of coupling means for coupling the electromagnetic energy of the dielectric resonator, located on one side of the ground plane, to the mixer diodes and also to the transmission line strips connected to the electrodes of the oscillator transistor located on the other side of the ground plane.